Recovery of caustic hydroxides from waste solutions



F. H. GRIFFIN- RECOVERY OF CAUSTIC HYDROXIDES FROM WASTE SOLUTIONS Filed June 27. 19 23 2 Sheets-$110.61: 1

mvEmo PR/smk JH- Gnu-TIN I ATTORNEYS Feb. 16 1926.

F. H. GRIFFIN RECOVERY OF CAUSTIC HYDROXIDES FROM WASTE SOLUTIONS 2 Sheets-Sheet 2 Filed June 27, 1923 BY Jinn MN ATTORNEYS mantra. 16,1926.

1nirfiaf1-1i 'oFFICE.

rmxn. umran, onwawa, rnnivsrnv'ama, assrenon r mun-viscose cou- PASNY, OI MARCUS HOOK, PENNSYLVANIA, A. CORPORA'JEION' O1 PENNSYLVANIA;

f nncovnnror'causric ir znnoxrnns rnou wasrn sonurrons.

. lApplication filed ilune 27, 1823. Serial lie. 848,082.

\To all whom it may concern: f

Be it known that I, FRANK H. GRIFFIN, a

citizen of the United States of America, re

"sidin at'Wawa, in the countyof Delaware and k tate of Pennsylvania, have invented certain 1 new and useful Improvements in, of Caustic Hydroxides from Recover Y Waste ol-utions. of which the following is a specification. Y 3

P My invention relates 'to improvements in the recovery of caustic hydoxides from waste,

. solutions, such as theliquor that results from the so-called steeping operation in jthei artificial silk industry, waste caustic liquors 'from the mercerization of yarns, and the so-cal-led black liquor from'the digestors of pulp mills using the caustic, method of cooking.

My invention contemplates the dialytic separation of the caustic hydroxides from impurities, such as hemi-celluloses, hydroxyicelluloses, oxy cellulose s and other substancesor anic or inorganic, which are con: tained in t 'e waste li uors either in solution .tion.' i v My invention furthermore embracesair propriate apparatus for carrying out the method and ,is shown -in one form in "the $0 accompanying drawings, in -which' or in flocculent, jellyike or colloidal conch-- Fig. Us a broken side elevation of a series of inter-connected tanks and associated dialytic cells Fig. 2 is a plan view thereof;

'Fig. 3:.is a broken side elevationof one of ihe dialytic cells alone, drawn to a larger sea e; r

Fig. 4" is a section on the line 3;v

:Fig, 5 is a perspective of the cell shown 'in F1g,4; and Fight is an enlargedcross sectionjot a detail. I

Although-diffusion .or dialytic methods have long practical y applied to the'recovery ofvalues P from waste caustic solutions, so far 1mm? 1 aware. In theart' to which m invention re-; ,mlt v 5 evaporate the liquor, followed-by the U relates, the eneral practice chip '1 cover the al ali from thespent .liquo" moval ofthe organic impurities by meagre.- tion orcarbonization, or by some m ma y ween been known they have never been :gipurg caustieieolution is introdu tical method and apparatus 'by which the all of the walls of which are'of semi-perm'eable membrane, the cellbeing immersed in a solvent for the caustic,- such as water, either pure or weakly caustic. The caustic "hydroxides of the waste liquor diffuses through the membrane and is taken up by the water,

but the organic impurities remain within the dialytic cell. -While I prefer to employ a plurality of water chambers .and associated dialytic cells, and to continuously flow the waste liquor throu h the several cells counter-current to the flow of water through the several compartments, both in series, the invention is not .so limited. .The cells may be worked separately or in'pairs, and they may be intermittentlycharged and discharged, if preferred. It is more satisfactory, however,

to employ ,the counter-flow principle for vwhich the apparatus shown in the drawings is designed. I

. R ferrin'g to thedrawings, I have here shown a. tank 15 sub-divided by partitions 16 into a series of independentcompartments one-en thisj'conipartment connection is madehy a.- pipe 18 to the upper portion of the adJacentd, b, a, (1,5, f, g, h, i,k. A pipe 17 delivers to the up er portion of thecompartm'ent k at d of the series. .From the bottom of v compartment '2. Preferably the outlet pipe 1.8 is at;.the opposite end of the comp'artment from the inlet ipe 1'], as well as at the 1 bottom thereofiwhi e the inlet 1s' at the top. Similarconnections by pgipes -18 establish theflow of the water throu' :the several com partments-in series, the'escap'e pipe 19 lead- -mg tog any"appropriate'receiving tank, ngt shown.) i .Within each the several compartme t I da dialytic cell 20 suitahlyj I s ced from e bottomand. slde wlll t e compartment mallow .of the ircu; lation-of the 7 water around the cell.

At. 0 top of thexce'll is a hood M99 made y the out:

21; barges nascent the bottbm thereof let pipe 23 leading to the cell in the adj aceiit chamber b from which in turn the liquor passes to the next c'ell in-series, and is finally discharged from the cell in compartment la through the outlet 24. Since the specific gravity of the liquor diminishes as it grad ually loses'jts caustic to the water by dialysis in the Successive compartments through which it passes, the hoods 22 metal body 25 by 'frame or their equivalents are desirable in order to compensate this loss of weight and to provide the'necessary head which causes the liquor to flow from cell to cell. It will he'noted that the level of the. liquor in the hoods is above that of the water in the surrounding compartments,

By properly regulating the supply of waste liquor entering at '21 and discharging at 2-.t,and also the flow ofthe we er entering at 17 and discharging at 19, the strength of the pure caustic solution which discharges from the pipe 19. may be controlled. The invention 1s not limited-to the recovery of 25 caustic liquors of any definite strength,'al-

though the maximum strength of the recov-' ered caustic depends upon the caustic strength of the waste liquor, the mannerin which the cells are. con led, and the rate: of flow through the es ls'and tankcompartments.

A satisfactory construction of one of the cells is indicated in Figs. 3 to 6. As here shown each cell comprises an open sided met'al body 25, having at its upper end a hood 22 and provided at its margins with out-turned flanges 26. The ermeable mem-. branes 27 which form the side walls of-the. cell are clamped to opposite sides of the lates 28' bolted .to the flanges 26. Vertical ars 30 may also be secured thereto, the lower ends of which project below the bottom of the cell and form supporting feet'31 which rest. upon the bottom of the compartment. Cross pins 32 at the-heads of the bars 30 afi'ord convenienthand holds during the-assembly and dissasse1nbly of the parts.

of parchmentized woven fabrics.

In order to clean the cells of sediment, pipes 33 (Fig. 3.) maybe introduced through the hood to the cell bottoms, and a suction connection made to the top ofithe pipe.

The diaphragms 27 may be of an suitable character, but I have found that (lbrability and cfli'ciency are best obtained by the use .Such membranes may be prepared by immersing cotton sheeting in sulfuric acid of specific gravity 'of 1.10 at a temperature of less than 30 C. for two minutes, followed by the removal of the excess acid either by neutral-1 ization or water-washing. -Whll0 the apparatus shown is eflicient for the carrying out of mymethod, various otherylayouts will readily occur to'those k lled in t a b etsm e r t e re tion.

I claim- 7 1. Dialytic apparatus,- comprising a series of compartments, means for tflowing a solvent therethrough in one direction in selying thoughts which I: claim:a smy. inven ries, in combination with a corresponding series of dialytic cells arranged insa'id compartments, and mea'nsfor flowing-the impure solution therethrough counter-current to the solvent, said cells having associated means for compensating the varying specific gravity of the impure solution as it passes through the-series of polls.

2. Dialytic apparatus, comprising a series to the solvent, each of said cells 'h'avingas-' sociated means for maintaining the neces-' sary head to insure the flow of the impure solution through the; cell series regardless 100 of its decreasing specific gravity as it ad- .vances'. y 4. In dialytic apparatus, a-cell comprisinga chamberhavmg a dialytic wall, and a bonnet at the top of with said chamber.

5. In dialytic apparatus, ing a chamber having a'dialytic wall, and a. bonnet atthe to of the cell communicating with said cham and a conduit passing down throu h the; chamber-,and opening adj of the latter.

ing a skeleton frame having continuous side flanges,

dialytic membranes. lying against acent the tt0m said flanges, clampin members registering with-said flanges, an

means for detachabl y securin -said clam in" members to the} flanges to' hold the membranes in position.

7.; In-dialytic apparatus, a .cell'compris ing a skeleton frame said, flanges, endless clamping frames registering' with said flanges, and means for se curing said frames to the flanges to clamp the membranesin position. 4

L 8. In dialytic apparatus, a cell comprising. a skeleton frame having continuous side fl anges,. dialytic membranes vof compartments, means for flowing a solflowing a.

pure solution therethrough counter-current! the cell communicating a tam-a es er,'a port inlsaid bonnet 6. In dialytic'apparatus, a cell compris 5 havingcontinuous side flanges, dialytic membranesly1ng against lying against n n i said flanges, clamping members for securing flanges, dialytic membranes lying against" said flanges, clamplng members for securing the membranes in position, and lifting members attached to the flanges and projecting 10 above the cell body.

10. Indialytic apparatus, 'a cell compris ing .a skeleton frame,- alateral dialytic membrane' secured thereto, .a sump 'in the .bot-

tom of the-cell and sport in the top of'the cellthro'ugh whicha-elean-outlpipe may be' introduce into the sump.

In testimony whereof I have signed myname to this specification."

' FRANK H; GRIFFIN. 

